POST MODERN ALCHEMY

A leap toward carbon neutrality? Transmuting carbon dioxide to methanol


By Dr. Tim Sandle
August 2, 2024


Madrid wants to ramp up production of emissions-free fuel like green hydrogen - Copyright AFP Valentin BONTEMPS

Researchers at the University of Michigan have developed a catalyst material known as cobalt phthalocyanine that converts carbon dioxide—a significant driver of climate change—into renewable fuels such as methanol.

The researchers studied using cobalt phthalocyanine as a catalyst to convert carbon dioxide into methanol through multiple reaction steps. The first step converts carbon dioxide into carbon monoxide and the second step converts the carbon monoxide into methanol. Methanol could potentially be used to power vehicles in a more environmentally friendly way.

Hence, the most-produced chemical worldwide can be generated environmentally friendly, serving as a base material for a wide range of industries and products.

This approach presents a sustainable method for reducing greenhouse gas emissions while offering an avenue to produce clean energy.

While the conversion of carbon dioxide to methanol has been industrialized, achieving this transformation on a large scale through electrochemical processes has proven to be a significant challenge.

Cobalt phthalocyanine acts like a molecular hook for carbon dioxide or carbon monoxide molecules. The arrangement of these molecules around the cobalt metal (the geometry) is crucial because it determines how strongly each gas molecule binds.

The problem, they found, is that cobalt phthalocyanine binds much more strongly to carbon dioxide molecules than to carbon monoxide molecules. Because of this, once carbon monoxide is produced in the first step, the carbon monoxide is displaced by another carbon dioxide molecule before it can be further converted to methanol.

Using advanced computational modelling, the researchers calculated that cobalt phthalocyanine binds carbon dioxide over three times more tightly than it binds carbon monoxide. They also confirmed this through experiments measuring reaction rates when varying the amounts of carbon dioxide and carbon monoxide.

The researchers showed that the difference in binding affinity has to do with how the catalyst’s electrons interact with the carbon dioxide and carbon monoxide molecules. To solve this issue, the researchers suggest redesigning the cobalt phthalocyanine catalyst to strengthen how it interacts with carbon monoxide and lessen how strongly it binds to carbon dioxide.

Resolving this roadblock should pave the way for using catalysts like cobalt phthalocyanine to efficiently convert carbon dioxide waste into methanol fuel on a large scale.

The research appears in the journal ACS Catalysis. The paper is titled “Electrochemical CO2 Reduction to Methanol by Cobalt Phthalocyanine: Quantifying CO2 and CO Binding Strengths and Their Influence on Methanol Production.”